The present inventive subject matter relates to the systems and methods Systems and Methods for the Reduction of Underwater Acoustical Noise
The protection and preservation of natural resources includes the management of fish and game. Fish move about lakes, rivers, streams and reservoirs for a variety of reasons, including migration, spawning, and searching for food. Furthermore, some fish species have such small populations that they are protected either under State or Federal laws (e.g. the endangered species act).
During the construction of roads it is sometimes necessary to drive pilings or other support structures into lakes, streams, and/or marshes. The driving of these pilings or other structures into the water creates acoustical vibrations. These vibrations can be of sufficient power to either injure or kill fish or other aquatic animals that are in the proximity to the vibrations. The issue of effect of sound underwater, known as bioacoustics, is of sufficient concern that the California Department of Transportation (Caltrans), the departments of transportation for Oregon and Washington, and the Federal Highways Administration have formed groups to study the impact on fisheries due to in-water pile driving.
Prior art acoustical mitigation devices include air bubble curtains, cofferdams, isolation casings, and cushion blocks. Air bubble curtains employ a bubble screen to reduce sound pressure. The drawbacks for bubble screens are the limited reduction in acoustical pressure. Cofferdams have greater acoustical reduction, but, are expensive to install and remove. Isolation casings have the drawback of less attenuation than cofferdams. Lastly, cushion blocks are placed in-between the hammer and the pile (in the case of pile driving). Cushion blocks likewise have limited attenuation properties as compare to cofferdams.
Therefore, there is a need to have a aquatic acoustical barrier proximate to underwater construction in general and near pile driving in particular. This barrier should have low cost, use readily available materials, and be easy to install and extract, and provide limited damage to the water environment.